Display Controller Vertical Blanking Period for Luminance Uniformity
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Solution Overview
Problem
Liquid crystal display devices experience motion blur and luminance difference/gradation unbalance at high refresh rates due to the slow response speed of liquid crystal molecules and uneven operation times of driving elements.
Innovation Solution
An image display device with a controller that determines the screen refresh rate, calculates the vertical blanking period, and adjusts the pixel clock frequency to control the operation of driving elements, ensuring synchronized light emission across the display panel, even at high refresh rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the refresh rate is increased to reduce motion blur, then the image clarity is improved, but luminance difference and gradation unbalance between horizontal lines occur due to different operating times of driving elements
Solution Approach 1:
The patent introduces a vertical blanking period before the active display period, during which the driving elements are pre-driven to reach their final state before light emission begins. This preliminary action ensures that all horizontal lines complete their driving operations synchronously, eliminating luminance differences between lines while maintaining high refresh rates
Solution Approach 2:
The patent divides the frame period into distinct segments: a vertical blanking period for driving element operation and an active period for light emission. This temporal segmentation allows the driving elements to complete their operations before the backlight emits light, ensuring uniform luminance across all horizontal lines even at high refresh rates
2Loss of time
If PWM dimming is used to improve motion blur, then the response time is reduced, but luminance difference and gradation unbalance occur at high refresh rates
Solution Approach 1:
The patent applies preliminary action by establishing a vertical blanking period where all driving elements complete their PWM dimming operations before the active display period begins. This ensures that even though PWM dimming is used for fast response, the luminance uniformity is maintained because all lines are fully driven before light emission starts
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Prevents luminance difference and gradation unbalance between horizontal lines by controlling the operation of driving elements before light emission, maintaining image quality at high refresh rates.
Implementation Method 1
by adjusting the intensity of an electric field formed in the liquid crystal during operation of the driving elements to change a tilt angle of liquid crystal molecules
Implementation Method 2
liquid crystal display (LCD) using liquid crystal
Implementation Method 3
a backlight unit configured to emit light to the display panel
Data Source
AI summary
Discussed are an image display device and an operating method therefor. An image display device can include a display panel that includes a plurality of pixels; a backlight unit that irradiates light to the display panel; and a control unit, wherein the control unit may determine a screen refresh rate for an image outputted through the display panel, determine a vertical blanking period for each frame in response to the determined refresh rate, calculate a pixel clock frequency corresponding to the determined vertical blanking period, and control, according to the determined pixel clock frequency, an operation of a plurality of driving elements disposed on the display panel which correspond to the plurality of pixels, respectively.